１．Abstract

Through industry-academia collaboration, we have developed a passive type of assistive suit that uses fabric mechanisms (mechanisms using a rubber belt or elastic cloth) for lifting motion in various situations such as logistics, factory lines, construction industry, agriculture, and nursing care. The industry-academia members often held training camps in the factory, we repeated trial production and experiments at the same time. Owing to this method, the development period was greatly shortened and finally the commercialization of product was achieved.

２．Contents of technology

Low back pain accounts for 60% of occupational illnesses in Japan, and medical experts say that it is desirable to bend the knees to lower the hips and take the posture of the “sonkyo” when lifting. In this case, a moment is applied to the extended arm, which increases the burden on the arm. Many active and passive devices for assisting the lower back have been commercialized, but most of them assist only the lower back, so women especially with no strength requested arm assistance. However, depending on the location, there may be fences, and so on, and the knees may not be able to be bent, so lower back assistance is also required. To address these problems, in the university’s creation class, a structure was proposed in which both arms and lower back were assisted with two belts (Fig. 1, left).

 Fig. 1 Fundamental structure of the suit and Belt 1

Belt 1 (Fig. 1 right) is the same as the conventional lower back assist suit, but with Belt 2 (Fig. 2 right, Fig. 3 left), when the knee is bent, the belt is pulled over the shoulder and the arm is raised. However, when the user twisted his hips, the arm belt on the twisted side loosened, and the opposite belt stretched, and the correct assistive force could not be obtained. Therefore, we proposed a mechanism that automatically adjusts the left and right belt lengths by utilizing the characteristics of fibers (Fig. 3, right). Various fabric mechanisms, such as a mechanism that increases the assistive force non-linearly when the back is bent, were proposed during frequent training camps in the factory by members of industry and academia such as teachers, students, and engineers in the company, then we repeated trial production and experiments at the same time. Therefore, the development period can be significantly shortened, and the product was commercialized in 3 years and started to be sold in 2019.

Fig. 2 Appearance of wearing the suit and Belt 2

Fig. 3 Structures of raising arms by bending knees and automatic adjust

The variation in muscle activity of the erector spinae muscles and biceps brachii muscles when this suit was put on, and a box of about 10 kg was lifted from the floor were evaluated to 7 healthy men in their 20s and 7 in their 50s. The results were obtained with a maximum reduction of 30-50%. In particular, since the muscle activity of the lower back is higher in the 50s than in the 20s, it is strongly recommended for the 50s to use some devices when lifting.

Reflecting the voices of the first version’s users, we made the new version of improvements in comfort and usability in 2021. Currently, it has been introduced by many companies in various industries, and we hope that the use of this suit will help reduce the burden on as many people as possible.

Eiichiro Tanaka,

Member，Graduate School of Information, Production and Systems, Faculty of Science and Engineering, Waseda University（2-7, Hibikino, Wakamatsu-ku Kita-kyushu, Fukuoka 808-0135）

Kenji Kodama,
Corporate member，Asahicho Corporation（110, Fukawa-cho, Fuchu-city, Hiroshima 726-0004）

Yun-Ting Liao,
Graduate School of Information, Production and Systems, Waseda University（2-7, Hibikino, Wakamatsu-ku Kita-kyushu, Fukuoka 808-0135）

Toshifumi Ishioka,
Asahicho Corporation（110, Fukawa-cho, Fuchu-city, Hiroshima 726-0004）

Chiaki Kanda,
Asahicho Corporation（110, Fukawa-cho, Fuchu-city, Hiroshima 726-0004）